1. Field of the Invention
The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device that controls the brightness of a backlight according to the intensity of incident external light, and a method of fabricating the same.
2. Discussion of the Related Art
Today, liquid crystal display (LCD) devices, are more widely used as a next generation display device because they enable a slim and lightweight design and have advantages such as low power consumption, high picture quality and easy mass production.
The LCD device includes a thin film transistor (TFT) array substrate and a color filter array substrate separated by a predetermined distance from each other, a liquid crystal layer between the two substrates, and a backlight providing light to the liquid crystal panel. The LCD device displays an image by adjusting the amount of light passing through the liquid crystal layer using the refractive anisotropy of liquid crystal molecules in the liquid crystal layer.
The backlight wastes power because it produces a constant brightness light to the liquid crystal panel even in a dark environment where not much light is required.
To solve the above problem, a system has been developed in which a light sensor sensing the surrounding brightness controls the brightness of the backlight, thus decreasing the power consumption of the backlight.
The light sensor is typically formed at an edge of the TFT array substrate facing a black matrix of the color filter array substrate, and the black matrix has an opening formed at a region corresponding to the light sensor.
At this time, in order to prevent light from the backlight from leaking through the opening formed in the black matrix, it is necessary that the corresponding liquid crystal of the liquid crystal layer should not pass incident light therethrough. That is, the portion of the liquid crystal layer positioned corresponding to the opening should be in a black state.
However, a voltage may be generated by the light sensor and a common electrode formed on the color filter array substrate to create an electric field that drives the liquid crystal of the liquid crystal layer, thus realizing a gray. In other words, light leakage occurs through the opening formed in the black matrix.
Also, the light sensor senses light passing through the liquid crystal molecules of the liquid crystal layer. If the liquid crystal layer near the light sensor is driven, the characteristic of the light incident into the light sensor may be varied. Therefore, the light sensor may fail to correctly sense the intensity of external light, so that the power of the backlight may be wasted due to a malfunction of the light sensor.